Most cancer-related deaths occur not from the first tumor to arise in a patient, but from cancers that reappear months or years after treatment. Scientists think that a group of rare cancer cells, called persister cells, might contribute to recurrence. Persister cells account for only a fraction of cancer cells, and, as their name suggests, persist under drug treatment and can potentially survive in the body long enough to gain new mutations that confer drug resistance, and drive recurrent tumor growth.
